io6 



University of California. 



[Vol. i. 



some part in bringing about the spheroidal and variolitic structures; 

 but the recorded observations of other writers do not lend much 

 support to this view. Thus, while Gregory* describes the diabase 

 of the Fichtelgebirge as showing an abundance of ilmenite and leu- 

 coxene, the analyses by Lcewinson-Lessingt of the Jalguba variolite, 

 and by Delesse % of the Durance occurrence, show no titanium. 

 This, however, does not necessarily prove its absence, unless it was 

 particularly sought for. 



Analyses of Eruptive Rocks of Point Boriita. 





I. 



II. 



III. 



IV. 



Si o 2 



49-45 



46.28 



45-59 



4471 



Ti 2 



2.23 



3-54 





2.88 



Al 2 O a 



1758 



12 96 



20.99 



15-54 



Fe 2 3 



3-4i 



4.67 



2.49 



3.06 



Fe O 



3-41 



606 



4-36 



6-43 



Mn O 



trace 



trace 





trace 



Ca O 



7.20 



10. 12 



7-57 



10.50 



Mg O 



4-05 



8.71 



8-95 



6.80 



Na 2 O 



5-8 3 



I 3 75 



4.89 



2.55 



K 2 O 



i-57 



/calc. as Na 2 



calc. as Na 2 O 



calc. as Na 2 O 



H 2 



ig- 4-34 



3-34 



ig. 5.06 



ig 5 90 



p. o 5 



not det. 



not det. 



not det. 



not det. 





99 07 



99 43 



99 90 



98-37 



Sp- gr 



2.738 



2.921 



2 707 



2.858 



I. Spheroidal basalt from exterior portion of large spheroid shown in 

 PI. 7, Fig. 2. 



II. Diabase, from the turn of the path just south of above spheroid. 



III. Diabase, near the fault line where crossed by path. Figs. 9 and 10. 



IV. Spheroid in the diabase about half way between B and C. 



THE SEDIMENTARY FORMATIONS. 



Character and Occurrence. — Leaving out of consideration the 

 unconsolidated deposits of Pleistocene age, the major part of the 

 sedimentary area is occupied by the San Francisco sandstone, which 



*Loc. cit., p. 54. 



■\Loc. cit., p. 294. . . 



% Bull. Soc. Geol. France, 2d s£r. t. vii, p. 430. 



